Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define sc second
#define mp make_pair
#define ps push
#define fr front
typedef pair<int,int> pii;//Be careful in topcoder.

#define MAX_H 50
#define MAX_W 50

string s[MAX_H];
int d[MAX_H][MAX_W];

int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

int main(){
	int h,w,ans=0;
	scanf("%d %d",&h,&w);
	for(int x=0;x<h;++x){
		cin>>s[x];
		for(int y=0;y<w;++y) if(s[x][y]=='.') ++ans;
		fill(d[x],d[x]+w,-1);
	}
	d[0][0]=1;
	queue<pair<int,int> > q;
	q.ps(mp(0,0));
	while(!q.empty()){
		int x=q.fr().fi,y=q.fr().sc;
		q.pop();
		for(int k=0;k<4;++k){
			int nx=x+dx[k],ny=y+dy[k];
			if(nx<0||h<=nx||ny<0||w<=ny) continue;
			if(s[nx][ny]=='#') continue;
			if(d[nx][ny]>=0) continue;
			d[nx][ny]=d[x][y]+1;
			if(nx==h-1&&ny==w-1) goto end;
			q.ps(mp(nx,ny));
		}
	}
	printf("-1\n");
	return 0;
end:
	printf("%d\n",ans-d[h-1][w-1]);
	return 0;
}